A Nuclear Reaction: Determining the velocity of neutrons

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Homework Help Overview

The discussion revolves around a nuclear fission reaction involving the collision of a neutron with a 235U nucleus, resulting in the production of 141Ba and 92Kr nuclei, along with two additional neutrons. The problem requires determining the speeds of the two neutrons after the collision, given specific initial and final velocities.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to apply conservation of momentum principles but expresses difficulty in resolving the problem due to perceived errors in their approach. Some participants question the identification of these errors and the significance of rounding in the final answers.

Discussion Status

Participants have provided feedback on the original poster's work, indicating that it appears correct while also highlighting potential issues with significant figures. There is an ongoing exploration of the calculations involved, but no consensus on the resolution of the problem has been reached.

Contextual Notes

The discussion includes references to specific values for the masses of the nuclei involved and the initial and final velocities of the neutrons, which may influence the calculations. There is also mention of rounding errors that could affect the interpretation of the results.

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Homework Statement



Fission, the process that supplies energy in nuclear power plants, occurs when a heavy nucleus is split into two medium-sized nuclei. One such reaction occurs when a neutron colliding with a 235U (uranium) nucleus splits that nucleus into a 141Ba (barium) nucleus and a 92Kr (krypton) nucleus. In this reaction, two neutrons also are split off from the original 235U. Before the collision, the arrangement is as shown in the figure (a). After the collision, the 141Ba nucleus is moving in the +z - direction and the 92Kr nucleus in the −z - direction. The three neutrons are moving in the xy-plane, as shown in the figure (b) (Figure 1) .[/B]

If the incoming neutron has an initial velocity of magnitude 3.0×10^3m/s and a final velocity of magnitude 2.0×10^3m/s in the directions shown, what are the speeds of the other two neutrons? (The mass of the 141Ba nucleus is approximately 2.3×10^−25kg, and the mass of 92Kr is about 1.5×10^−25kg.)

Homework Equations



Pi_x=Pf_x

Pi_y=Pf_y

The Attempt at a Solution



I have tried this problem several different ways and keep getting stuck. I have been told my approach is correct, however there are some errors present. Can someone please help me through this problem. Thank you
IMG_0502.jpg

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Hello. Welcome to PF.

Your work looks good to me. How do you know there are errors present? Your final answer for Vn1 has been rounded to only one significant figure.
 
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TSny said:
Hello. Welcome to PF.

Your work looks good to me. How do you know there are errors present? Your final answer for Vn1 has been rounded to only one significant figure.
T

here was a rounding error, the final answer is 220 m/s and 1000 m/s

Thanks
 
OK. Good work!
 
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